Need say circle to be visualized as a half sphere!

I'm a pretty techy guy and could not figure out what I was looking at for a bit. I think that it needs to be said that the circle is best visualized as a half sphere with the circle's center the closest point on the sphere to the viewer (or something like that!). Because I was looking at the graphic as a circle (that is "flat surface") I could not interpret the crescent shaped yellow zone. I am a little familiar with viewing the sky and after a while realized the upper and lower paths of the sun across the (spherical, from my point on the ground) sky! Then I could see what the yellow zone meant. Perhaps label the upper path as "summer solstice" and the lower as "winter solstice" and put in another for "spring and fall equinox". Not sure having a yellow "zone" has much meaning.

Also, you have directions (sunrise, sunset positions) described as lines on a flat surface within what I think is the spherical graphic representation of the sun paths across the sky. This is confusing to look at for me.

Perhaps if the half sphere was covered with some faint lines of longitude it would be more easily recognized as a half sphere above a more or less flat map with sun rise/set directional lines.

Hope I visualized the graphic correctly or all this will not make sense!